This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Brave New World
The Huxley novel
For John, the hundreds of human clones who he describes as "long rows of identical midgets" and "human maggots squirming over beds of death."
For many readers, the idea of being born and pre-programmed on an assembly line, possibly waiting to be made mentally handicapped, and being forced into a caste position for the rest of your life. And nobody is going to mourn you after you die.